A hydraulic actuator in a drum brake assembly includes a pair of pistons which are slidably disposed within a bore on the hydraulic actuator. The pistons engage a pair of brake shoes in order to urge the brake shoes into engagement with a drum to effectuate braking. When braking is terminated, a return spring retracts the pistons and brake shoes away from the drum; however, elastomeric return seals such as illustrated in my U.S. Pat. No. 3,377,076, also serve to retract the piston and brake shoe lining, provided a connecting structure between the piston and brake shoe exists.
When an elastomeric return seal is used with a hydraulic actuator on a drum brake, it is desirable to retract the pair of brake shoes from a rotatable member, when braking is terminated, through a predetermined distance equal to a running clearance. However, retraction of the pistons and brake shoes should be limited to this predetermined distance so that the pistons and brake shoes need only travel through the predetermined distance upon a subsequent brake application.